The grounding of the Rena on Astrolabe Reef created one of New Zealand's worst maritime disasters.
Photo: RENA PROJECT

The consultants' reports estimate full wreck removal would cost up to $US540 million and would take just over five years.

A spokesperson for the owners, Hugo Shanahan, said the review offers only one of many expert opinions the judge will weigh up when a decision is made on the application.

A resource consent application to leave the Rena wreck on the Astrolabe reef is to be heard by the Environment Court.

Mr Shanahan suggests the Bay of Plenty's Regional Council's report due in November will give a more accurate picture of the Rena's situation.

In 2011, the container ship crashed into the Astrolabe Reef, off Tauranga, spilling tonnes of oil and debris into the sea and creating one of the country's worst maritime and environmental disasters.

The Rena is owned by Greek shipping company Costamare through one of its subsidiaries, Daina Shipping Company.

London Offshore Consultants - an international marine and engineering consultancy - was asked to peer review documents that owners submitted to support their resource consent application to leave most of the wreck on the reef.

In its submission on the resource consent, the Government called for only parts of the wreck in shallower waters (above 30 metres) to be removed.

After the submission, lodged last month, Prime Minister John Key said the cost to remove the wreck would be too high and Attorney-General Chris Finlayson said full removal of the wreck could put the safety of workers at risk.

But the consultants' reports say the container ship's owners had grossly exaggerated the timescale and costs. They estimate that full wreck removal would cost between $US422 million and $US540 million and would take just over five years.

London Offshore Consultants say if an offer of full wreck removal was put out to international tender "then solutions would be offered that may prove to be far less costly".

The Government wants the part of the wreck in water down to 30 metres removed. Photo: RENA PROJECT

Selective approach, consultants say

The consultants also say the ship's owners had not considered all the options for full wreck removal and point out that an offshore crane could be used.

The author says the owners have been selective in their approach "which allows the authors to accommodate a pre-determined conclusion".

The Rena's owners point out the risk full wreck removal could have on the safety of the divers who are employed to remove the wreck.

But the consultants say that there is such a thing as a diver-less removal operation.

London Offshore Consultants has also told the Government that in similar wreck situation across the world governments tend to demand that wrecks be removed.

The reports say: "The fact that some of the wrecks posed little or no threat to either the environment or safe navigation made no impact upon the relevant authorities' decisions to impose total wreck removal notices."

The Rena's owners' resource consent application will be heard in the Environment Court. The application for that hearing is expected to be lodged in mid-October.

A lawyer for a Motiti Island hapu group fighting in the Waitangi Tribunal for the removal of the ship is concerned about the release of the reports.

Janet Mason said the reports should have been disclosed to all claimants who are before the tribunal. Lawyers are seeking instruction on what to do next.

The Government will not push for the full removal of the wreck of the container ship Rena from Astrolabe Reef, off the coast of Tauranga, because of the health and safety risk and substantial cost. Video, Audio